#include"stack.h"

void STInit(ST* ps)
{
	assert(ps);
	ps->a = (int*)malloc(sizeof(int) * 4);
	if (ps->a == NULL)
	{
		perror("malloc fail");
			return;
	}
	ps->capacity = 4;
	ps->top = 0;
}
void STDestroy(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
}
void STPush(ST* ps, STDataType x)
{
	assert(ps);
	if (ps->top == ps->capacity)
	{
		int* tmp = (int*)realloc(ps->a, sizeof(int) * ps->capacity * 2);
		if (tmp == NULL)
		{
			perror("relloc fail");
				return;
		}
		ps->a = tmp;
		ps->capacity *= 2;
	}
	ps->a[ps->top] = x;
	ps->top++;
}

bool STEmpty(ST* ps)
{
	assert(ps);
	return ps->top==0;
}

void STPop(ST* ps)
{
	assert(ps);
	if (!STEmpty(ps))
	{
		ps -> top--;
	}
}
int STSize(ST* ps)
{
	assert(ps);
	return ps->top;
}

STDataType STTop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));
	return ps->a[ps->top - 1];
}